1. Field of the Invention
The present invention relates to a system for removing loose debris from streets and other surfaces. Particularly, the present invention relates to snow or ice removal from regular and irregular surfaces. More particularly, the present invention relates to a system that can be configured to perform various ground cleaning operations. More particularly yet, the present invention relates to a snow removal system that fractures the snow covering a surface, lifts the fractured snow from the surface, and discharges it through an impeller/discharge system. Most particularly, the present invention uses a stiff but flexible stepped triple finger mechanism to fracture and lift the snow and deliver it to an impeller assembly that transfers the snow and laterally discharges it, at an adjustable height above the surface from which it is expelled.
2. Description of Prior Art
Although the utility of the present invention is not limited to snow removal, the relevant prior art lies in the field of snow removal mechanisms. Among the many different means for removing snow from ground surfaces snowplows are the best known. Nevertheless, snow removal by snowplow has a number of inherent disadvantages. A snowplow typically requires several passes to clear a roadway of snow. In the first pass, it clears a swath, discharging the snow to the side of the plow, thereby creating snowbanks that narrow the roadway and impair visibility for vehicle operators or pedestrians. In a subsequent pass or passes, the plow works at pushing the snowbank further away from the roadway. Furthermore, highway snowplows typically require a certain minimum forward speed if the plows are to impart to the snow the velocity needed for the snow to travel across the face of the plow. In congested traffic conditions in which the snowplow is prevented from maintaining this minimum speed, snow spillage may occur at the edge of the plow not intended to discharge snow, leaving ridges of snow in the middle of the roadway or causing the vehicle to stall. Also, snowplow blades are straight and rigid, designed to remove snow from regular surfaces. When they contact fixed protrusions from the surface, these blades may become bent or damaged in other ways, requiring costly repair or replacement. Also, the plow blade does not remove the snow from the ground cleanly, but rather, leaves surface recesses filled with snow.
Snowblowers have certain advantages over plows: they do not require a minimum forward velocity of the prime mover in order to move the snow and, depending on the orientation of the discharge outlet and the throw speed, they may avoid creating snowbanks at the roadside. Yet, there are also disadvantages inherent to snowblowers, existing in all of their many types. Snowblowers typically engage the snow by means of cutters, brushes, or augers, and transport the snow to a blower unit which discharges it to either side of the snowblower at some distance from the roadway. Cole (U.S. Pat. No. 2,103,514; 1937) teaches a system that uses a pair of rotary cutters to engage and then transport the snow or ice to a centrally located blower unit, which then discharges the snow or ice to either side of the vehicle as desired. Another system teaches the use of a rotary drum having blades located around its periphery to cut and lift snow and convey it to a discharge unit Maxfield et al. (U.S. Pat. No. 5,209,003; 1993). The rigidity of augers or cutters, as taught by the systems of Cole or Maxfield et al. creates several difficulties. For one thing, the leading edge of an auger or a rotary cutter is necessarily exposed to allow engagement with the snow; these rigid, churning augers or cutters make such snowblowers inherently dangerous to use. Furthermore, rigid augers and cutters can damage--or be damaged by--roadway protrusions, such as manhole covers or bridge joints, and, consequently, must be operated at some distance above the level of the surface to be cleared. This practice leaves residual snow on the surface. This means that systems that use augers or cutters can be used only in conjunction with other snow removal means, physical or chemical, if the snow is to be completely removed.
Snow blowers do exist that use brushes rather than rigid augers. E.g., Klauer (U.S. Pat. No. 2,941,223; 1960) teaches a manually operated system that uses two spiral brushes, oppositely wound around a rotating shaft, to transport snow to the center of the shaft. Alternatively, Maisonneuve et al. (U.S. Pat. No. 3,886,675; 1975) teaches the combined use of a rotating brush and an auger to engage snow and transport it to the blower unit. Rotating brushes, unlike rotating cutters and augers, can be operated in direct contact with the ground surface. Brushes, however, have a disadvantage in that the bristles in the brushes are round and, thus, only the snow particles that hit the leading edge of the bristles are propelled forward. All others are deflected laterally to varying degrees. Brushes also require a great deal of power to engage and lift the snow. This is because, typically, every bristle contacts the ground and, thus, every bristle bends, its tip contacting the ground. This results in the leading edge of the bristle actually facing downward before the bristle tip starts its desired forward and then upward movement as the tip loses contact with the surface. As a result, the snow is initially driven downward before it is propelled upward and forward. This results in a packing of the snow, making it more resistant to being passed through the rest of the device. Furthermore, since all the bristles drag on the ground, they encounter a frictional force that works against the direction of the brush rotation. This increases the power demanded to maintain that rotation at an effective rate.
As described above, snowblowers with brushes, augers or rotary cutters typically transport the snow to a centrally situated blower unit for expulsion. This means that the snow is handled for an extended period of time, as it travels from the outer edge of the snow collection means to the center, or, when dual snowblowers are used, as it travels from the center of snow collection device to the outer edges. The longer the snow remains in the system, the greater the volume of snow that is being handled or transported at any given time. Thus, snowblower systems must be designed to accommodate these large volumes and provided with the power required to move them. Also, the fact that snowblowers pack the snow as it is handled means that more power is required to transport the snow then would be the case with loose fluffy snow. Furthermore, the high-density, packed snow often causes the equipment to jam, leading to interruptions and potentially hazardous operations to clear the device.
Snow or debris removal systems are generally dedicated systems, i.e., a snow removal system is designed to remove only snow, a street sweeper is designed to remove only dirt and loose debris from the ground. As a consequence, cities, towns, and other entities that must be concerned with removing snow or debris from ground surfaces are required to invest in multiple costly devices to perform various necessary ground cleaning operations. It would be of great advantage if a system for removing snow and other debris could be rapidly and easily reconfigured as required to perform various ground surface cleaning operations, such as removal of frozen slush or fallen leaves or other loose debris, in addition to snow removal.
Therefore, what is needed is a snow removal device that will cleanly and safely remove snow from ground surfaces and discharge the snow without creating snowbanks that narrow the roadway or impair visibility. What is further needed is such a device that will fracture the snow into small, light units, thereby improving the operating speed, efficiency, and safety of such a device. What is yet further needed is such a device that will cleanly remove snow from irregular ground surfaces. What is still further needed is such a device that can be rapidly and easily reconfigured to perform various ground surface cleaning operations.